Beginner question: Collision is not working
Based on the comment i would suggest the following solution:


Make a copy of the container object, adding a "-simhelper" at the end allows for easier identification later.
Select the copy and adjust the thickness of the solidify modifier to at least the size of the objects that are gonna fall in. Explanation a bit below.
Make the copy invisible in render by going in the Object Properties, under Visibility un-check the Show in Renders and in Viewport Display un-check the Shadow and maybe set the Display As to "Bounds".

This way the simulation helper object will not bother you in the viewport or render.
Select the simhelper object and then the original, make sure the original is highlighted as yellow, active, and press Ctrl+P "Object", making the simhelper a child of the original, in case you have to move the original later.
Now you can disable the "Rigid Body" on the original
Test the simulation and adjust the thickness of the solidify modifier as needed.


Little Explanation:
The Reason for using a thicker simulation helper is that the simulation uses sub-steps to catch an intersection, if the object falls to fast and passes through the walls without being caught by the simulation, it keeps falling and results in your problem situation.

Happy Blending